Phonographic apparatus



Feb- 18, 947- s. APPLEBY 2,416,135

PHONOGRAPHIC APPARATUS Filed June 4, 1945 Patented Feb. 18, 1947 PHONOGRAPHIC APPARATUS Sidney Appleby, Toronto, Ontario, Canada, as-

.signor of one-half to David Appleby, Toronto,

Ontario, Canada Application June 4, 1945, Serial No. 597,447

6 Claims.

My invention appertains to photographic apparatus and particularly to apparatus for recording and reproducing sound wherein the sound is recorded photographically upon a disc in the form of an uninterrupted spiral.

In apparatus of this kind it has already been. proposed to provide a spiral track scanning device which is guided across a transparent disc record by means of a spiral groove engaged with a pin or stylus, and in which there is provided a photoelectric cel1 subject to variations in light intensity in accordance with the movement of the sound record for controlling a sound reproducing system.

The general object of the present invention is to provide an improved apparatus of this type which is adapted to employ an inexpensive form of sound record by whichtit is particularly suitable for use in homes as well as for commercial purposes. The sound record may comprise a disc of a thin flexible base, such as Celluloid, etc., coated with a photosensitive emulsion in which a spiral sound track has been recorded.

A further object of the invention is to provide a structure by which the sound record can be readily inserted and removed from the apparatus.

on. The record disc is comparatively inexpensive to manufactur and use.

The record disc is placed upon a turntable 1 of transparent material such as glass or the like, which is carried by a spindle 8 projecting from I a conventional motor 29. It will be evident that A still further object is to furnish an apparatus in which the sound record is securely clamped in place and protected against dust and defacement.

Still another object is to furnish a structure in which the pin or stylus which-travels in the guide groove is relieved of the weight of the scanning member so that a smooth action ensues and friction is minimized.

With these and other objects in view the in vention consists in the novel construction and ar rangement of parts as described in the ensuing specification and more particularly defined in the appended claims.

The accompanying drawing illustrates a selected embodiment of the invention, in which Fig. 1 is a plan view of the, apparatus.

Fig. 2 is a cross section on line 2-2 of Fig. 1.

Fig. 3 is a perspective View of the sound record.

Fig. 4; is a fractional side view of the scanning device.

In carrying out the invention a sound record is provided in the form of a thin flexible disc 5 of transparent material such as Celluloid having a surface treated with a photographic emulsion and exposed to light fluctuations representative of sound and subsequently developed to provide an opaque spiral sound track 6 therethis is the ordinary mode of rotating the turntable about its central axis as is common to the phonographic art.

In order to hold the record disc in a flat condition upon the turntable there is provided a guide plate it which is a circular member of transparent material and which by its own weight serves to clamp the record disc. The guide plate is of a diameter approximating that of the turntable and is hingedly connected to the same at one side, as at H, so that it may be raised and lowered to provide for removal and insertion of the record disc. The guide plate is supplied with a knob 22, preferably centrally located as shown, by which it can be conveniently manipulated.

The upper surface of the guide plate is supplied with a spiral groove 9 for th purpose of guiding a sound track scanning member IS inwardly over the covered record disc as it is rotated. Said guide groove has the same pitch as the sound track throughout the length thereof and passes between the turns of the same. A stylus or pin it coacts with said guide groove to inwardly move the scanning member l3 in known manner. The scanning member is car-* ried by an arm by which the required traversing movement is achieved under uidance of the spiral groove 9. Well known means may be resorted to for starting and stopping the mechanism. The sound track it and the spiral groove ii have a common geometrical centre when the record disc is placed on the turntable. The record-disc is also mounted with respect to the guide plate so that the beginning of the sound track coincides with the beginning of said spiral groove. This is desirably accomplished by the provision of a circular series of apertures [6 in the record disc which fit over a corresponding number of pins il upstanding from the turntable. The pins ll preferably engage in'apertures 18 in the guide plate.

The scanning member is of a known type in which light from a suitable source within the casing thereof is focussed at l9 on the sound track 6 by an optical system also disposed within said casing and having its optical axis coinciding substantially with the centre line of the track 6. After passing through the guide plate It, the

3 I record 5 and the turntable 1 and being modulated by the sound track, the light strikes a photoelectric cell 213 below the turntable. Said photoelectric cell is preferably of the stationary type in which the active element of the cell extends substantially radially across the disc record so as to be in line with the path of movement of the scanning member i3. Said cellis connected to a suitable amplifier, not shown. 7

An important feature of construction is that the stylus or pin functions solely as an element of the guide means for the scanning member 13 and does not support the scanning member. The Weight of the scanning device is supported by a pad 2i of felt or other suitable material of a like texture which is secured to the same and rests upon the guide plate 10. The stylus or pin terminates short of the bottom of the spiral groove and therefore only makes contact with its side walls. This reduces wear on the guiding connection and lessens friction. Additionally the felt pad serves as a wiper to brush off any traces of dust from the guide plate,which is a decided advantage in the sound reproduction.

While the invention has been described in its preferred form, such changes and variations may i b resorted to as come Within the spirit and scope of the subjoined claims.

What I claim is:

1. In phonophotographic apparatus, the combination of a transparent turntable, a transparent disc record in the form of a thin flexible film having a spiral sound track recorded on one surface thereof, a transparent guide plate rotatable with the pitch of said spiral soundtrack, a scanning member mounted for movement over said guide plate, means associated with said scanning member and arranged tocooperate with said guide groove for causing said scanning member to be fed across said disc record in the operation of said turntable, and a wiper pad engaging said guide plate in the movement of said scanning member and having a supporting connection with said scanning member.

2. In a phonophotographic apparatus, a transparent turntable having an upper face receptive to a disc record having a spiral track of recorded sound thereon, a transparent guide plate for bearing upon said disc record to hold it flat and even on said turntable, means connecting said guide plate to said turntable for rotation there with, said means including a hinge by which the guide plate may be swung away from the turntable, and a spiral stylus guiding groove provided on the upper surface of said guide plate-for feed- I ing a scanning device acrossthe sound track of said disc record in the operation of said turntable.

3. A structure as defined in claim 2, in which the means for connecting the guide plate to the with said turntable and disposed to bear upon said disc record to hold it fiat when it is mounted on the turntable, said guide plate being hingedly connected to said turntable and provided with a spiral guide groove in its upper surface conforming to the pitch of said spiral sound track, a scanning member mounted for movement over said guide plate, and means associated with said scanning member and arranged to cooperate with said guide groove for causing said scanning mem..

her to be fed across said disc record in the operation of the turntable. a

6. In phonophotographic apparatus, the combination of a transparent turntable, a transpar ent disc record in the form of a thin flexible film having a spiral sound track'recorded on one surface thereof, a transparent guide plate rotatable with said turntable and disposed to bear upon said disc record to hold it fiat when it is mounted on the turntable, said guide plate provided with a spiral guide groove in its upper surface conforming to the pitch of said spiral sound track, a scanning member mounted for movement over said guide plate, a pin projecting from said scanning member for engaging said guide groove for causing the scanning. member to be fed across said disc record in the operation of the turntable, and means providing a. bearing surface for said scanning member in supporting engagement with the upper face of said guide plate to prevent said a pin from sliding on the bottom of the spiral guide I'OOVe.

SIDNEY APPLEBY.

REFERENCES ciTEn The following references are of record in the file of this patent:

UNITED STATES PATENTS 

